competitive cyclist's arm measurement description:

Continue to hold the cylindrical object and extend your arm in front of you, holding your arm parallel to the ground. Try not to allow your shoulder to come forward. Make sure that the object in your hand is perpendicular to your arm. Locate the Pivot of the arm to shoulder point and measure from this point to the center of the object, which should fall in line with your knuckles. Measure both arms and average the measurements.